The present invention relates to an assembly for a fuel injection system for use with an internal combustion engine, and more particularly to an assembly for a fuel injection system of a type such that a fuel injector is provided for each cylinder of the engine.
In general, a fuel injection system of this type includes fuel injectors mounted adjacent to a cylinder head of the engine in an engine compartment. As a result, each of the injectors tends to be heated by heat of the engine, so that temperature of the injector is increased, which may cause the generation of fuel vapor. If the fuel vapor is generated in the injector, a predetermined quantity of fuel cannot be injected during a predetermined operating period of time of the injector, causing a trouble that mixture of lean air-fuel ratio is supplied to the engine.
Generation of the fuel vapor in the injector mainly results from two causes. One is that fuel vapor generated in a fuel passage for supplying fuel to the injector is fed into the injector, while the other is that fuel vapor is generated in the injector itself. In order to prevent the generation of the fuel vapor due to the former cause, a technique is disclosed in Japanese Patent Publication No. 61-24544. However, the technique cannot prevent the generation of fuel vapor due to the latter cause. The latter cause tends to occur especially when the engine temperature remains high after the engine is stopped due to the stoppage of operation of an engine cooling system. In other words, if a measure to be taken for the latter cause is insufficient, troubles may occur at restarting of the engine.
In the conventional fuel injection system of the above type, each fuel injector is provided for each cylinder, and the fuel passage must be connected to each injector. The connection between the fuel injector and the fuel passage must be accurately effected so that the fuel may not leak out. As a result, mounting operation becomes troublesome and machining accuracy of each part must be kept high, which in general causes an increase in manufacturing cost of such a fuel injection system.
The fuel injection system of the above type includes a further problem in responsiveness of the engine, because, when atomized fuel injected from the injectors is deposited on inner walls or the like of an intake manifold, it may take more time for the injected fuel to reach the cylinders of the engine. In order to avoid this problem, it is required to provide a structure ensuring that the injected fuel can reach the cylinders of the engine as smoothly as possible.